The principal goals of this project are the development of algorithms that allow one to make the best use of NMR data to determine solution structures of biomolecules, to assess in a systematic fashion their accuracy and precision, and to explore the extent to which dynamical information can be extracted from NMR data. This will involve the following components: New models for chemical shifts in biomolecules. We will develop automated quantum chemical/molecular mechanical (QM/MM) models to compute chemical shifts and anisotropies in proteins, carbohydrates, and nucleic acids. Results will be used to examine conformation flexibility in ubiquitin, helix junctions in DN and RNA, and conformational flexibility in collagen peptides. Studies on protein and nucleic acid dynamics. Long-time scale molecular dynamics simulations will be used to model NMR relaxation, with attention paid to anisotropic tumbling, to the correlation between internal and overall motions, and to conformational disorder. Analytical models with adjustable parameters will be constructed to allow direct fits to experimental data. This will include an analysis of contributions from both overall and internal motions to chemical shift anisotropy (CSA) relaxation and to CSA-dipolar cross-correlated relaxation. Principal applications will be to elongated molecules such as duplex DNA and collagen, and to proteins with a folded core domain and a disordered tail region.